ES2913252T3 - Method and apparatus of a modular management system for energy storage cells - Google Patents

Abstract

A management system for rechargeable energy storage devices comprising energy storage cells connected in series (B1, B2, B3, B4, Bn) and a control unit (9), characterized in that said management system further comprises - a cell division circuit (2) comprising switches (S9, S10) configured to divide the series-connected energy storage cells (B1, B2, B3, B4, Bn) into groups of cells, - a circuit ( 3) mode selection comprising switching devices and a single ohmic device (5) and wherein the switching devices are configured to select any of: a) externally powered cell balancing, wherein balancing of the externally powered cells is a mode of passive balancing during charging or discharging of rechargeable energy storage devices, b) internally powered cell balancing, in which balancing d e internally powered cells is a series and parallel mode balancing during a sleep time, and c) an internally powered diagnostic test for estimation of state of health or state of charge, in which a group of cells of said groups of cells divided with the cell division circuit (2) is adapted to apply a driving current to test another group of cells of said groups of cells, and wherein said individual ohmic device (5) determines a level of the balancing current for said passive balancing and for said series and parallel mode balancing.

Description

DESCRIPTION

Method and apparatus of a modular management system for energy storage cells

The present invention relates to management systems, methods and devices such as modular management systems, methods and devices for monitoring, balancing and/or protecting a pack of energy storage cells such as battery cells and for estimating the state of a cell or cells such as the state of health (SoH) and/or the state of charge (SoC) of a cell or cells.

Background/State of the art

Rechargeable energy storage systems (RESS) play an important role in many applications, such as smart grids and electric vehicles (EVs). The performance of the RESS management systems needs to improve. For example, rechargeable storage cells in series must produce a sufficiently high output voltage and the available power must be optimized. Preferably, a balancing circuit should be provided to ensure that the change in voltage and capacity of the rechargeable storage cells is almost the same during the process of charging and discharging. In addition, voltage, current, and temperature must be monitored to protect the RESS from overcharging, overdischarging, or overheating.

Three or four main functions are required for any BMS:

1) monitor voltage, current and temperature,

2) Balance the voltage and capacity of rechargeable storage cells,

3) estimate the SoH (State of Health) and/or the SoC (State of Charge) of each cell, and

4) Optionally protect the RESS against overcharging or overdischarging or overheating.

Conventional management systems have a passive or active balancing circuit. Commercially, passive balancing is popular. Passive balancing can be used to balance the voltage and capacity of power cells in rechargeable energy storage systems by using multiple resistors that dump excess power into higher power cells during charging and charging operations. download. However, this process wastes energy and causes an unwanted local temperature rise, and therefore additional energy consumption is needed for cooling. Another procedure using active balancing loses less energy, but it is a complex and expensive system. These drawbacks are caused by the additional components (ie capacitor or inductor with resistors or DC/DC converter) that are needed to transfer power from higher power cells and then to inject this power into lower power cells.

Another aspect of RESS is detecting the health status/remaining capacity of rechargeable storage cells. The state of health (SoH) is the storage cell's ability to store and retain energy, and therefore whether its performance or health deteriorates can be determined.

Various procedures have been developed to estimate the health status of energy storage cells. Most of them are based on a capacity test or exact models, which depend on the electrochemical characteristics and dynamics of the storage cell. The estimation of the SoH based on the capacity test needs a long test time (>2hr) due to the fact that the cell must undergo a charging and discharging process. In addition, the cost of the unit of measurement is affected by the charge/discharge current, which depends on the nominal capacity of the tested cell.

In the case where a dynamic model is used, its accuracy can be increased if a system model is constituted by higher order equivalent circuits, but this is too complex a practical use.

Several studies on battery BMS design have been reported in the literature as follows: US Patent Application No. 2014/0097787 describes a BMS for actively balancing battery pack voltages and capacities. An array of power transfer units, which are integrated in parallel and individually connected to the cells of the battery pack to balance the cells. However, like most previous studies, there is a directly proportional relationship between circuit complexity and efficiency. For example, the BMS can be designed to decrease power and heat loss, but a complex circuit must be used by using additional components such as power transfer units, storage elements, and switches.

To clarify the previous attempts to design the BMS, the two parts should be investigated: the balance mode and the test mode (estimation of SoH and/or SoC).

In the case of balancing, US Patent Application No. 2014/0232346 describes a system that includes an active cell balancing circuit configured to balance multiple power cells connected in series within a single module.

As a further example, US Patent Application No. 2013/0093248 discloses that multiple batteries are connected in series through the use of an active balancing circuit. The active balancing circuit includes an LC resonance circuit and multiple switches configured to selectively couple different batteries to the LC resonance circuit.

A disadvantage of these systems is that they require a relatively long balancing time compared to the passive balancing circuit. Furthermore, the complexity of the system increases due to the use of storage elements, such as an inductor and/or a capacitor with the necessary accessories.

Some battery systems use a simple circuit to balance the batteries. These systems are described, for example, in US Patent Application No. 2013/0293006, which describes that a parallel connection can be used to balance series-connected batteries. However, additional resistors are needed to control the equilibration current and time, and additional switches must also be used to change the cell connection from series connection to parallel connection. In US Patent Application No. 2014/0145651, the present invention relates to a circuit that allows balancing cells with reduced circuit complexity by using a single resistor. However, when only a passive balancing technique is implemented, there is no significant effect of reducing the number of resistors on the power and heat loss of the balancing circuit.

In the case of test mode, in some older battery monitoring systems, an undesirably long test is required to assess the SoH of the battery. This is especially the case for systems, which require the battery under test to be fully charged before a health measurement can be made. As an example, US Patent Application No. 5,977,750 describes a system for calculating battery SoH by tracking the degradation of a battery's full charge capacity with cycles.

Some battery monitoring systems measure a series of electrochemical parameters and use fuzzy logic to calculate the state of health of the battery as described in US Patent Application No. 7,072,871. As a further example, US Patent Application No. 2011/0060538 discloses that the battery SoH can be estimated by calculating a range of voltages by taking the convolution of a battery chemical terminal current with a range of responses to an impulse from a lookup table of impulse responses corresponding to different health states. In US Patent Application No. 2014/0306712, the invention describes that two voltage levels and a battery impedance are determined. A table of battery impedances is used to calculate the SoC and SoH of battery systems.

A disadvantage of these battery monitoring systems is that they need to store the history of the parameters for that particular battery and thus increase the complexity of the system.

On-Board Diagnostics (OBD) is a technical term from the automotive industry. Refers to a vehicle's self-diagnostic and reporting function that allows the vehicle repair technician to access the status of the vehicle's various subsystems. The OBD system was introduced in the early 1980s and has developed based on changes in vehicle on-board computers. Recent OBD systems use a standardized digital communications port to provide real-time data, as well as a standardized series of Diagnostic Trouble Codes, or DTCs, to quickly identify and correct vehicle malfunctions. Some battery monitoring systems measure AC impedance at 1 kHz using very small sinusoidal signals. The AC impedance at this frequency is also called the "resonance impedance" and attempts have been made to find a relationship between the health of the battery and the resonant impedance. These systems are described, for example, in Kazuhiko. T, Quick testing of batteries in lithium-ion battery packs with impedance-measuring technology, Journal of power sources 128 (2004) 67-75. However, external components (ie a function generator with switches) are required to apply a small sinusoidal signal to calculate the AC impedance of the battery cell. Also, only one type of lithium-ion battery is used to "prove" that there is a linear regression between resonance impedance and remaining battery capacity. In practice, due to the use of a very small sinusoidal signal, an advanced filter is needed to remove the influence of noise and interference from surrounding devices.

In EP2490315A1, a cell balancing module is described in which a resistor is used for passive balancing and in which an external charger, namely a DC-DC power converter, can also be used to supply loads to the cell. drums. All battery cells are connected in series.

In US8648602B2, an impedance detection system for a battery is described. A dedicated injection circuit is described for separately injecting current into individual battery cells for testing purposes.

In US7274170B2 a battery pack control module is described in which a discharge resistor is used to balance the series connected cells of the battery pack.

Objective/Purpose

There remains a need to develop an energy storage cell management method, system and device, preferably in a modular form that, for example, as an option improves on one or more disadvantages of the prior art. Embodiments of the present invention address these advantages such as providing one or both of these:

1. Passive/active balancing and test modes (eg, a diagnostic test to estimate the SoH/SoC) are performed efficiently without using external sources or additional components (eg, a capacitor or inductor) thanks to an arrangement of dedicated switching devices using bidirectional devices and unidirectional switches optionally connected to a single ohmic device such as a resistor.

2. A simple and modular cell balancing system, which can be used for a wide variety of different energy storage cell designs, such as some or all battery technologies to balance in such a way that the loss of heat is low or less and/or there is low or less energy consumption;

3. An effective test, which can be used quickly, reliably and easily, for example as an OBD status check without using an external source, for example to estimate the SoH and/or SoC of fuel cells. energy storage or cell packs such as batteries.

Summary of the invention

In one aspect of the present invention, embodiments relate to a method, system, and management devices for multicellular rechargeable energy storage systems (RESS). In embodiments of the present invention, the same configuration can be used to monitor and/or protect and/or balance and/or charge and/or test and/or control a RESS comprising rechargeable power cells. For example, RESS cells can be connected in series. In other embodiments of the present invention, methods, systems and devices are provided to balance the cells with the advantages of less energy loss and, therefore, a decrease in heat loss, which results in a system optionally low power compact cooling unit for a balancing circuit.

In another aspect, the present invention provides a management system such as a modular management system comprising bidirectional and unidirectional switches connected to a power dissipation device, for example, a single ohmic device, such as a resistor to efficiently execute a balanced passive/active, and a test mode for SoH/SoC estimation which can be described as a dual function process (DFP) preferably without using any additional or external components (i.e. capacitor or inductor or DC/DC converter or power supply).

Embodiments of the present invention describe a management system as a modular management system for rechargeable energy storage devices comprising:

series connected energy storage cells,

a cell dividing means such as a cell dividing circuit for dividing or separating series-connected power cells into groups of cells, the cell dividing means or the cell dividing circuit comprising first switching devices bidirectional; Y

a control unit,

the system comprising: a mode selection circuit comprising the first one-way switching devices, the first one-way switching devices of the mode selection circuit being adapted and configured to allow the selection of a management mode selected from any of a balancing mode or a test mode or a charging mode or a discharging mode of operation,

further comprising a current balancing circuit having second bidirectional switching devices, a balancing current, which can be drawn from or injected into any one or more of the rechargeable power cells passing through the battery balancing circuit current, the second bidirectional switching devices being adapted to allow the control unit to select a balancing current to flow to or from a cell.

In embodiments of a balancing circuit or method, an ohmic device, such as a resistor, is used (or a limited number of ohmic devices are used, e.g., fewer than five or fewer than three) to achieve balancing of a or more energy storage cells such as batteries in a pack by using two balancing modes:

1) embodiments in passive balanced mode, for example, with a single ohmic device such as a resistor, and,

2) Embodiments with an internally powered RESS balance mode including series and parallel connected embodiments. Passive balancing embodiments function on both charge and discharge to at least partially balance rechargeable power cells, such as batteries. These embodiments can keep the capacitance and voltage differences around a threshold limit thanks to an arrangement of dedicated switching devices. Therefore, rechargeable energy storage cells can be protected against overcharging or overdischarging during fast charging and deep discharging, respectively. By using the same ohmic device, e.g. For example, a single ohmic device such as a resistor, thanks to the provision of dedicated switching devices, the internally powered RESS balancing mode, including both series and parallel balancing embodiments, can use some or most of the part of, or all of a standby time (idle time) to fully balance the voltages and capacities of the rechargeable power cells by changing the cell connections, e.g. i.e. series to parallel. The same setup can be used for SoH estimation by using the AC impedance test mode. Different RESS topologies can be integrated and used together in the same energy storage system by using embodiments of the present invention.

Embodiments of the present invention provide systems, methods, and devices for multicellular RESS modules/packets. Multi-cell RESS modules/packages are commonly used in applications such as: electronic devices, medical equipment, automotive and stationary applications, and in transportation vehicles to connect series-connected rechargeable energy storage cells. With these multi-cell RESS packs/modules, cell imbalance can occur and some rechargeable energy storage cells can age faster than others. Imbalance can occur, for example, due to slight differences in SoC, self-discharge rate, capacity, impedance, or temperature characteristics of rechargeable energy storage cells that are connected in series. Even for cells that have the same technology from the same manufacturer and even come from the same production lot, aging may not be uniform for all cells.

For example, unevenness in aging rates and levels may result from a very small variation in sizing or a chemical composition or temperature distribution effect during operation. As a result, the internal resistance of these rechargeable energy storage cells can increase, which can lead to failure over time. If only one storage cell fails, the entire module also fails due to the serial connection. Therefore, an effective management system must be used to ensure that all rechargeable storage cells age at the same rate. Alternatively, energy storage cells, such as batteries, can develop self-discharge, uneven current distribution, and an internal short circuit. This can result in the cell overheating and even in an explosion.

Embodiments of the present invention may provide one or more of the following:

• procedures, and/or RESS balancing systems and/or devices, which provide balancing with low or less energy and/or heat loss;

• a simplified cooling system and/or procedure and/or device for a balancing circuit in order to reduce energy consumption and, optionally, reduce the total cost of operation;

• arrangement of a dual function process (DFP), which means dividing or separating the rechargeable power cell pack, such as a battery pack, into two or more independent (isolated) modules, each comprising cells of the rechargeable power cell pack, such as a battery pack. Each split module is configured to perform a dual function, such as a DC power supply of its own, and each of those modules can be used as a means to balance and/or apply a DC pulse (eg. , without using an external power supply) to another such module in a RESS to perform a diagnostic test, e.g. eg estimate the SoC or SoH of the storage cell(s) thanks to the arrangement of the dedicated switches (bidirectional and unidirectional switches optionally connected to a single ohmic device such as a resistor);

• provision of a modular balancing circuit, system and/or procedure, which can be used to balance different RESS technologies;

• provision of a generic and/or rapid and/or simple test procedure, and/or test system and/or test device to estimate the SoH or SoC of rechargeable power cells such as batteries;

• Provision of a flexible RESS procedure and/or system and/or device that can be integrated with different types of power electronic converters.

Embodiments of the present invention provide, for example, one, some, or all of:

• A modular management system and/or method and/or device for rechargeable energy storage cells or cell packs with a new configuration, by using bidirectional and unidirectional switches optionally connected to a single ohmic device such as a resistor.

• A modular management system and/or method and/or device comprising a group of switches (such as bidirectional and/or unidirectional switches), for example with an individual ohmic device such as a first resistor to provide a flexible circuit and/or or system and/or procedure that allows operation for different applications and/or allows integration with other circuits. Also, optionally, a second ohmic device, such as a resistor, can be connected in parallel with the single ohmic device, such as the first resistor, to change the internal resistance of the balancing circuit, and thus the balancing rate. .

• An energy storage system and/or method and/or device for small and large scale applications with good e.g. i.e. high efficiency.

• The modular management system, procedure or device may comprise bidirectional and unidirectional switches connected, for example, to a single ohmic device, such as a resistor, to effectively manage the rechargeable energy storage cells during the operating process and time. idle idle.

• The modular management system, method or device may comprise bidirectional and unidirectional switches with, for example, a single ohmic device such as a resistor used to protect rechargeable energy storage cells that are connected by a series switch arrangement.

• The modular management system, method or device may comprise bidirectional and unidirectional switches with, for example, a single ohmic device such as a resistor adapted to perform two balancing modes to avoid any imbalance between the rechargeable energy storage cells.

• The modular management system, procedure or device may comprise bidirectional and unidirectional switches with, for example, a single ohmic device, such as a resistor used with a group of cells, for example, to provide a DFP for a test mode using applying a drive current to test another group of cells.

• The modular management system, method, or device adapted to perform two balancing modes providing a passive balancing mode during charging and discharging, and an internally powered balancing mode that includes a series and parallel mode during a idle sleep time.

• The modular management system, procedure or device in which the passive balancing mode is adapted to protect rechargeable energy storage cells from overcharging or overdischarging.

• The modular management system, method or device may comprise an internally powered balancing mode including a series and parallel mode that is adapted to complete the balancing of the rechargeable energy storage cells during an inactive standby time.

• The modular management system, procedure, or device in which the test mode (optionally based on a DFP) is adapted to apply an excitation current signal (for example, a square or quasi-square wave or bandwidth modulation). pulse). Subsequently, a response voltage signal is measured without using external power. These signals are then converted from the time domain to the frequency domain by using a series of orthogonal waveforms, such as in the discrete Fourier transform, to calculate the AC impedance as a function of frequency levels. .

• The modular management system, procedure, or device in which AC impedance is measured to provide a value for an internal impedance of rechargeable energy storage cells, especially the AC impedance at 1 kHz, which is called the impedance of resonance.

• The management system, procedure or device in which the resonance impedance is calculated and used to estimate the SoH or SoC of rechargeable energy storage cells using a generic aging model. The generic aging model can relate the resonance impedance to the state of charge. For example, in the model, the resonance impedance can be defined by: im yfsófi+c ■ in which A, B and C are constants.

• The modular management system, procedure or device can be integrated into a network through the use of a single stage, a double stage or a multi-port and/or multi-level converter.

• A modular management system for rechargeable energy storage systems comprising energy storage cells connected to each other in a cell array, the system comprising: a control unit for deciding the mode of operation, such as the mode of balanced, test, or protection, a voltage sensor array to measure a voltage of each cell in the energy storage pack individually, a current sensor to determine whether the energy storage pack's operating type is charging, discharging, or sleep, controllable switches to select a balanced mode for the cells or a test mode for the cells, the balance mode which is one of passive, series and parallel balanced, and a controller that receives the output from the voltage sensors and current and to control the controllable switches so that when the cells are charged or discharged, the outputs of the voltage are sent to the controller, and based on a comparison of the received outputs, the controller adapts to initiate passive balancing mode, and when the operating mode is idle, the controller adapts to initiate passive balancing mode. series and parallel followed by a test mode to estimate the SoH and/or SoC.

• Controllable switches can include unidirectional and bidirectional switches.

• One-way switches can be used to select modes of operation (passive or series-parallel or test).

• Bidirectional switches can be used to control the current direction to or from the cell depending on the mode of operation and also to split the packet.

• Balancing modes can be realized, for example, with a single ohmic device in series thanks to the smart switch arrangement.

• A test mode can be carried out, for example, by using a dual function process (DFP) to avoid the use of an external power supply thanks to the provision of dedicated switches (bidirectional and unidirectional switches optionally connected to a single ohmic device such as a resistor) in order to estimate the SoH and/or the SoC.

• A mode of protection may include disconnecting the battery pack in the event of a fault.

• The control unit can be connected to the interface circuits by using the communication unit to display the status and performance of a packet.

Embodiments of the present invention provide a system, method, or device that can be used for different applications, for example, any of the following:

• Life-first connection, ie new energy storage cells, such as in battery storage modules for automotive smart grid applications;

• Connecting second life energy storage cells, such as in battery modules, which are removed from automotive applications, to other smart grid applications;

• Integrate different rechargeable energy storage technologies in a specific application.

• Flexible integration with an auxiliary energy storage system, such as in a battery storage system and renewable energy systems (eg, wind turbine, tidal power generation, geothermal heat or power generation systems, or photovoltaic or the like), by arranging dedicated bidirectional switching and/or unidirectional switching devices including a mode selection circuit and a current balancing circuit.

A separate invention includes a system, method, or device for estimating the SoH of rechargeable energy storage cells using a generic aging model. The generic aging model can relate the resonance impedance to the state of charge. For example, in the model, the resonance impedance can be defined by: im yfsóH+c ■ in which A, B and C are constants.

In another aspect, a management system or modular management system for rechargeable energy storage devices is provided comprising series connected energy storage cells, bidirectional and unidirectional switches connected to a single ohmic device such as a resistor for executing effectively a dual function process (DFP) (eg passive/active balancing and test mode for SoH/SoC estimation) preferably without using any additional or external components.

The DFP provides for the division or separation of the rechargeable power cell pack, such as a battery pack, into two or more independent modules, each divided module performing a dual function, such as being a DC power source. Each such module can be used as a means to balance and/or apply a DC pulse (without using external power) to another such module in a RESS to estimate a state such as the SoH of the cell(s). s) storage by means of a dedicated switch arrangement (eg bidirectional and unidirectional switches preferably connected to a single ohmic device such as a resistor); and a control unit.

In another aspect, there is provided a system for use in any embodiment of the present invention comprising: a mode selection circuit comprising bidirectional and unidirectional switching devices optionally connected to a single resistor, the switches being adapted and configured one-way switches of the mode selection circuit to allow selection of a management mode selected from a balance mode or a test mode or a charge or discharge mode of operation, further comprising a current balancing circuit having switches bidirectional switches, a balancing current, which may be drawn from or injected into one or more of the rechargeable power cells passing through the current balancing circuit, the bidirectional switches being adapted to allow the control unit to select a current balancing to flow to or from a ce energy storage lda.

In another aspect, a system for use in any of the embodiments of the present invention is provided having a mode selection circuit comprising a group of switches (eg, bidirectional and unidirectional switches) optionally connected to an ohmic device. individual, which determines the level of the balancing current and executes a dual function process to allow selection of a management mode. The management mode can be selected between a balance mode or a test mode or a load or unload mode of operation.

In another aspect, a dual function process may be used in any of the embodiments of the present invention in which one group of cells is used to apply a drive current to test another group of cells without using any external power. One group of cells can be adapted to apply a drive current to test another group of cells, whereby a means is provided for measuring a response voltage signal in the drive current. After dividing the series-connected power cells into groups of cells with bidirectional switches, a balancing current is drawn or injected into one or more of the rechargeable power cells by using bidirectional switching, the bidirectional switches that are adapted to select a balance current to flow to or from a cell.

The balance current level can be determined by using an additional ohmic device connected in parallel with the ohmic device alone.

In another aspect that can be used in any of the embodiments of the present invention, a drive current is applied to test a group of cells with another group of cells.

For example, an externally powered balancing mode may be a passive balancing mode during charging or discharging of rechargeable energy storage devices, and internally powered cell balancing may be a series and voltage balancing mode. parallel during a rest period. Passive balancing mode can be adapted to protect rechargeable energy storage cells from overcharging or overdischarging. Series and parallel mode can be adapted to complete the balancing of rechargeable energy storage cells during standby or idle time.

One group of cells may be configured to apply a drive current to test another group of cells further comprising means for measuring a response voltage signal in the drive current. The response voltage signal can be converted from a time domain to a frequency domain, e.g. by using an orthogonal set of waves or wavelets, e.g. For example, by using a discrete Fourier transform, the AC impedance can be calculated as a function of frequency levels. An SoH of rechargeable energy storage cells can be calculated by using such AC impedance. The SoH of rechargeable energy storage cells can be calculated by using a generic aging model.

Brief description of the figures

Figure 1 illustrates a modular management system according to an embodiment of the present invention.

Figure 2 illustrates an embodiment of the present invention for four battery cells.

Figure 3 illustrates a flow diagram of the operation of the battery management devices of Figure 1 according to an embodiment of the present invention.

Figures 4a to d illustrate four cases of passive balancing mode operation according to one embodiment of the present invention during charging using a single resistor a) battery cell B1, b) battery cell B2, c) battery cell B3 and c) battery cell B4.

Figures 5a to d illustrate four cases of operation of the passive balancing mode according to an embodiment of the present invention during discharge by using a single resistor: a) battery cell B1, b) battery cell B2, c) battery cell battery B3 and d) battery cell B4.

Figure 6 illustrates switched shunt ohmic resistors (passive balanced) using multiple ohmic resistors in accordance with one embodiment of the present invention.

Figures 7a and b illustrate the cell voltages of a passive balancing simulation: a) multiple ohmic resistance (R=1.5 Q) and b) single ohmic resistance (R1=1.5 Q) according to an embodiment of the present invention. Figures 8a and b illustrate the cell SoC of a passive balancing simulation: a) multiple ohmic resistance (R=1.5 Q) and b) single ohmic resistance (R1=1.5 Q) according to an embodiment of the present invention.

Figures 9a and b illustrate the passive balancing simulation power loss: a) multiple ohmic resistance (R=1.5 Q) and b) single ohmic resistance (R1=1.5 Q) according to an embodiment of the present invention.

Figures 10a and b illustrate the results of simulating a passive balancing mode using a single resistor during charging: a) voltage and b) SoC according to an embodiment of the present invention.

Figures 11a and b illustrate the simulation results of a passive balancing mode during discharge: a) voltage and b) SoC according to an embodiment of the present invention.

Figures 12a to d illustrate four cases of operation of the series and parallel balancing mode according to an embodiment of the present invention during sleep time by using a single resistor: a) transfer power from the battery cell 3 and the battery cell 4 to battery cell 1, b) transfer power from battery cell 3 and battery cell 4 to battery cell 2, c) transfer power from battery cell 1 and battery cell 2 to battery cell 3, and d) transfer power from battery cell 1 and battery cell 2 to battery cell 4.

Figure 13 illustrates an embodiment of the present invention for four integrated battery cells with a separate DC charger.

Figures 14a and b illustrate the cell voltage of a balancing simulation: a) series and parallel mode (R1=1.5 Q), and b) passive balancing mode using a single ohmic resistor (R1=1 .5 Q) according to an embodiment of the present invention.

Figures 15a and b illustrate the cell SoC of a balancing simulation: a) series and parallel mode (R1=1.5 Q), and b) passive balancing mode using a single ohmic resistor (R1=1.5 Q). .5 Q) according to an embodiment of the present invention.

Figures 16a and b illustrate the power loss of a balancing simulation: a) series and parallel mode (R1 =1.5 Q), and b) passive balancing mode using a single ohmic resistor (R1 =1 .5 Q) according to an embodiment of the present invention. Figure 17 illustrates the control strategy based on the PWM technique (where n is the number of RES cells such as battery cells connected in series) according to an embodiment of the present invention.

Figure 18 illustrates a pulse signal based on the PWM technique according to an embodiment of the present invention. Figure 19 illustrates a flowchart of the proposed methodology for estimating SoH and/or SoC according to one embodiment of the present invention.

Figures 20 a and b illustrate AC impedance test mode simulation results: a) drive current and b) response voltage according to one embodiment of the present invention.

Figure 21 illustrates the AC impedance of batteries as a function of frequency level as used in one embodiment of the present invention.

Figure 22 illustrates the generic aging model for SoH estimation based on experimental tests of different types of lithium-ion batteries as used in one embodiment of the present invention.

Figure 23 shows the relationship between SoH and resonance impedance for LFP (Lithium Iron Phosphate) and NMC (Lithium Nickel Manganese Cobalt Oxide) batteries tested with different sizes.

Figure 24 shows actual SoH values versus predicted SoH using one embodiment of the present invention.

Definitions

A "bidirectional switching device" refers to one or more switches and diode devices, which selectively allow current to flow in one of two directions through the switching device. The switches can be discrete components such as reed relays in parallel with a diode. Alternatively, the switches may be transistors. The diodes can be discrete components or can be, for example, a transistor connected to a diode.

A "unidirectional switching device" refers to one or more switches, and optionally diode devices, that selectively allow current to flow in only one direction through the switching device. The switch or switches can be discrete components, such as a reed relay in series with a diode. The diode can be a discrete component or it can be a transistor connected to a diode, for example. Alternatively, the switches may be individual transistors configured to allow current in only one direction.

An "ohmic device" is an electronic device that behaves like, or is, one resistor, or is two or more resistors, e.g. eg, in a resistance circuit, which follows Ohm's law. Therefore, the current flowing through an ohmic device varies proportionally to the voltage across the device.

A "dual function process" (DFP) means dividing a rechargeable power pack, such as a battery pack, into two or more independent modules through the arrangement of dedicated switches (e.g. bidirectional and unidirectional switches optionally connected to a single ohmic device, such as a resistor).

An "AC Impedance Rechargeable Energy Storage Cell Health Diagnostic" is an estimation procedure and/or technique that enables an RESS management system to estimate a diagnostic parameter (i.e., being a, or related to a, or derivative of, or a function of a SoH) of a cell or cell pack. The SoH of rechargeable energy storage cells can be estimated from the results of applying an AC impedance test mode. Additional or alternative diagnostic tests may be used with the present invention and are, for example, current, voltage, and resistance or impedance diagnostic tests, e.g. eg, as indicated in US 4,719,427 and US 4,361,809.

Detailed Description of Illustrative Embodiments

The present invention relates to a modular management system for rechargeable energy storage cells or cell packs with a new configuration and advanced settings to provide an intelligent layout. The same configuration supported by the management system is designed to monitor, protect, balance, charge, test, and control a RESS that is connected in series.

Figure 1 and Figure 2 illustrate a management circuit according to an embodiment of the present invention. This system has two groups of switching devices or switches: a current balancing circuit (1) comprising bidirectional switching devices, comprising bidirectional switches S1, S2; S3, S4; S5, S6; S7, S8; S11, S12; S13, S14; S15, S16; S17, S18. A mode selection circuit (3) is provided comprising the unidirectional switching devices or switches S19...S23 and a cell division circuit (2) comprising the bidirectional switching devices or switches S9, S10. A balance current, which can be drawn or injected into any one or more of the rechargeable power cells B1 to B4, passes through the current balance circuit (1), e.g. g., consisting of bidirectional switching devices. The bidirectional switching devices of the current balancing circuit (1) may comprise, or may consist of, two switches (i.e. S1 and S2; S3, S4; S5, S6; S7, S8; S11, S12; S13). , S14; S15, S16; S17, S18) each switch is coupled in series with a first diode device and each switch is coupled in parallel with a second diode device, as shown in Figure 2, whereby a diode D1 for example is connected in reverse compared to the other diode D2. These switching devices or bidirectional switches (1) allow a control unit (9) to select a balancing current to flow to or from a cell.

The mode selection circuit (3) comprises unidirectional switching devices or switches S19...S23, which include individual switches such as transistors S19, S20, S21, S22, S23 and S24 (see Figure 2), are adapted and configured to allow selection of a management mode such as a balance mode or a test mode or a load or unload mode of operation. A test process such as a DFP, for example, may be performed by a split circuit (2) configured to split the rechargeable power cell pack, such as a battery pack, into two or more separate modules. The division circuit (2) can include a series connection of bidirectional switching devices or the switches S9, S10 which can divide the cell pack B1 to B4, into an upper module B1+ B2 and a lower module B3 B4 or for a any number of cells. Each split module is a power supply in itself and each such module may be used as a means to balance and/or test another such module in an internally powered RESS balancing or diagnostic process embodiment . This can avoid the need for an external power supply for balancing or testing processes, although the provision of an external power supply external power supply is not excluded from the scope of the present invention, although it is less preferred. As shown in Figure 2, the series-connected switches S9 and S10, with the reverse-connected diodes D9 and D10 respectively connected in parallel to the switches S9 and S10 represent the serial bidirectional switching device for modulizing. Since the current required to balance and test the battery cells is relatively low (i.e., less than 5 A), there is no need to increase the parallel redundancy of unidirectional and/or bidirectional switches or switching devices. used in the present invention, which represents economic infeasibility. However, the charge/discharge current passes through the switching devices or switches (S9, S10), which therefore need to pass relatively high currents (i.e. > 50 A), depending on the size of the system. of batteries, capacity and load demand. Therefore, in practice, a series connection of bidirectional switches or switching devices (S9 and S10) can be extended with more switches or switching devices connected in parallel (as shown in the inset of Figure 2) to share battery current during discharge and charge modes, and to reduce the cost and size of these switching devices or switches. A single ohmic device (5) such as a resistor R1 can be used for balancing and/or testing. One or more additional but optional ohmic devices (6), such as resistor R2, may be added in parallel to resistor R1 to increase balancing current and decrease balancing time. Each such additional ohmic device is preferably controlled by an additional switching device or switch.

The voltage of each rechargeable power cell B1 to B4 is individually monitored by a voltage detecting means (4). The voltage sensing means (4) may be provided by an array (4) of voltage sensors, whereby one of these sensors can be adapted to measure the voltage of a cell B1 to B4. Alternatively, a sensor can be switched to a cell to be measured (not shown). The voltage sensing means (4), such as the voltage sensor array, may communicate with a central control unit (9) and thus have a means to communicate the results of the voltage measurement to the host. central control unit (9). The central control unit (9) has a means to receive the results of the voltage measurements (e.g. I/O port, or network or bus interface) and also has a means to store these values (i.e. , memory) and to process these values (i.e. rendering engine).

The temperature of the battery pack is monitored with a temperature measurement means such as a temperature gauge (12). The temperature of the package is also communicated to the central control unit (9) and therefore the temperature measurement means has means for communicating the results of the temperature measurement to the central control unit (9). . Therefore, the central control unit (9) has means to receive the results of temperature measurements (e.g. I/O port, or network or bus interface) and also has means to store (i.e. i.e. memory) these values and to process these values (i.e. a processing engine).

The current of the rechargeable power cell pack, such as a battery pack, is monitored with a current monitoring device (7) and the current values that are the results of the current measurements are communicated to the unit ( 9) central control. Therefore, the current monitoring device (7) has means for communicating the results of the current measurement to the central control unit (9). The central control unit (9) has a means to receive the results of the current measurements (e.g. I/O port, or network or bus interface) and also has a means to store these values (i.e. , memory) and to process these values. (i.e. a processing engine).

The voltage of the energy storage pack is preferably also monitored and the values, which are the results of the pack voltage measurements, are communicated to the central control unit (9). Means are provided for measuring the pack tension and for communicating the results of the pack tension measurement to the central control unit (9). Therefore, the central control unit (9) has a means to receive the results of the packet voltage measurements (e.g., I/O port or network or bus interface) and also has a means to store these values (ie memory) and to process these values (ie a processing engine).

The performance of rechargeable energy storage cells, such as batteries, may be based on one, some or all of the above measured values and accumulated during operation of the balance and/or test modes. The performance can be displayed on a user screen, such as an LCD device (11), or can be communicated to the outside (the outside world) through an interface, such as an I/O port, a network interface or a bus, such as a CAN bus, or a serial connection such as a USB port. The rechargeable energy storage cell pack, such as a battery pack, preferably has means for disconnection, e.g. via a protection relay (8) under the control of the central control unit (9) in case of failure or to carry out a self-powered diagnostic test on board.

Figure 3 illustrates an operational flow chart of one embodiment of the present invention. To ensure data accuracy, it is preferable that all data, such as pack voltage, current flow, cell voltage, and cell temperature, be calibrated initially and preferably automatically. First, each cell voltage, pack voltage, pack current, and temperature are frequently measured by the relevant sensors (4), (7), (12), etc., and transmitted to the unit (9). of controller. Next, a control algorithm according to embodiments of the present invention that is executed in the control unit (9) processes this data by using a processing engine to decide and implement the package management system function(s) to be performed. The control unit (9) has a digital processing engine such as a microprocessor or an FPGA, as well as memory. The control unit (9) can be configured as a stand-alone device, e.g. eg, it can be configured as a microcontroller or it can be configured as an embedded or embedded control unit. The control unit (9) has sufficient processing power and memory to implement the management systems and execute the procedures according to the embodiments of the present invention.

The procedure flow 100 of Figure 3 begins with step 102. At the beginning and before the management system function(s) to be performed are initiated, it is preferable that certain security checks be performed. One of these safety functions, preferably performed by the control unit (9), is to check the pack voltage V ^p to ensure that the RESS cell pack is safe for use. For example, the RESS cell pack voltage V ^p , the charging current IL supplied by the RESS cell pack and the RESS cell pack temperature T ^b are measured at step 104 using the sensors 4, 7 ), (12) relevant, etc., and can be communicated to the control unit 9 and the values are buffered or stored there. In step 106, the measured packet voltage V ^p is compared to a maximum value V ^max by the controller (9) and optionally compared to a minimum value V ^min . The control unit (9) can carry out one of these comparisons or both comparisons. If the measured pack voltage V ^p exceeds the maximum value V ^max the RESS cell pack is disconnected (eg by the control unit (9) sending a disconnection signal to the protection relay (8), at step 108 to enable repair or investigation. If a pack is fully discharged, the pack voltage V ^p can be close to zero, so a low value is not necessarily a fault. However, if the packet voltage V ^p is less than a minimum threshold value V ^min the flow can also optionally exit in step 108. If step 106 is YES, the current sensor (7) and more preferably if the unit (9) control, you can check if the RESS cell pack is in charge or discharge operation (109) or rests in idle mode (110). For example, in step 111 the control unit (9) can check if the load current is zero, indicating an inactive state (110). If step 111 is NO, the control unit (9) can check, in step 112, if the charging current is greater than zero indicating a state (109) of charge (or state of discharge, depending on how it is arranged). The circuit). If step 112 is NO, the control unit (9) checks in step 113 if the charging current is less than zero indicating a state of discharge (or charge). During the charge/discharge operation (109), the voltage sensors (4) continuously communicate the voltage data to the central control unit (9) to determine if there are any cells with poor performance. If the answer is YES at steps 112 and 113, a poorly performing cell can be determined, for example, by comparing a minimum cell voltage to a maximum cell voltage value of some or all of the cells in the storage pack. rechargeable power, such as a battery pack. For example, once this voltage difference exceeds a threshold value as in step 114, e.g. exceeds 80 mV, the control unit (9) starts the passive balancing mode, e.g. at step 115. The passive balancing mode can be implemented for at least partial balancing of the cells in the rechargeable energy storage package, such as a battery pack, by using a single ohmic device, such as a resistor. At the same time, the heat loss from the RESS cell pack is preferably monitored to control the cooling system in order to maintain the temperature of the balance circuit and/or the RESS cell pack below a maximum temperature, e.g. e.g. around 35 °C. For example, at step 117, the control unit 9 checks whether the package temperature T ^b is less than a maximum temperature such as 35°C. If the answer is YES at step 117, the passive balance mode continues until the voltage difference determined at step 115 is below a threshold value such as 80 mV, at which time control restarts at step 104. If in step 117 it is NO, the control unit (9) starts a cooling system in step 119 and the flow returns to step 114.

Various additional steps (not shown in Figure 3) may be performed, such as entering step 108 (eg, under the control of control unit (9)) if there is an indication that the cooling is not controlling the temperature of the cell pack and/or balance circuit properly. For example, if in several consecutive time periods step 117 is NO, it may indicate that the packet is out of control and step 108 can be entered (eg, under the control of control unit (9)). ). Alternatively, step 117 may include the control unit (9) checking whether the package and/or balancing circuit temperature ^Tb is less than a first maximum balancing circuit temperature, such as 35°C, and does not exceed a second maximum package temperature, such as 55°C or 80°C. In case the second maximum package temperature is exceeded, step 108 is entered (eg, under the control of the control unit (9)). Furthermore, steps 112 and 113 may include the control unit 9 performing the further step of checking whether the charging current is greater than a maximum absolute value. Exceeding said value could indicate a short circuit and therefore the controller (9) enters step 108.

If the answer is YES in step 111, it is assumed that the RESS cell pack is idle (110) and the flow goes to step 120 where the control unit (9) checks if there is a difference between the maximum cell voltage and the minimum cell voltage of the cells of the RESS cell pack is less than a certain value, eg. g., less than 6 mV. In case of idle operation (110), one or more modes can be preferably selected, e.g. depending on the order of operation. For example, if step 120 is NO, the control unit (9) initiates a series and parallel balancing mode at step 121 and at a later time step, the flow returns to step 120. If the series and parallel balancing mode works correctly, it will fully balance the cells and the check at step 120 will reveal that the voltage difference measured at that step is less than a threshold value, eg. g., less than 6 mV. Various additional steps may be performed (not shown in Figure 3), such as entering step 108; for example, if the series and parallel balancing mode fails to reduce the voltage difference in step 120 after a long period of time.

If step 120 is YES, a test mode can be started at step 122. Prior to step 122, the RESS can be disconnected from any load by use of the protection relay (8), for example under the control of the control unit (9). At step 122, an on-board diagnostic test, e.g. e.g. fed by several cells in one part of the RESS. For example, the diagnostic test may be the determination of an estimate of an SoH of RESS cells such as battery cells. From additional steps, such as steps 122 to 124, the end of life of the cells in the RESS packet can be determined, e.g. by identifying weak cells, which, for example, indicate poor SoH based on an AC impedance diagnostic test, e.g. have high AC impedance (i.e., greater than 15 mü) at step 123 or defective cells such as open circuited cells or shorted cells detected at step 124. The results of steps 122 or 124 may displayed on the screen (11) or communicated to a user in any other suitable way, e.g. eg, through an I/O port or through a bus such as a CAN bus. Any defective cell can be replaced or the entire pack can be replaced.

The operation of a RESS cell pack based on the battery management circuit structure in Figure 2 will be described based on the simulation results of a four-cell lithium-ion battery RESS cell pack.

Passive balancing mode

During the charging and discharging process 109, the passive balancing mode in step 115 may function directly to at least partially balance the battery cells through the use of a single ohmic device (5) such as a single resistor (R1 of Figure 2). Figure 4 and Figure 5 illustrate four cases of passive balancing mode operation during charge/discharge. The function of the switches or one-way switching devices (S19, S20...S23 in Figure 2) is to connect the individual ohmic device (5) such as the individual resistor R1 and a battery cell B1-B4 in parallel, which has the most energy, based on the location of the battery cell in battery pack B1 through B4.

Figure 4a illustrates the ^RESS cell pack of Figures 1 and 2 subjected to a charging current Ich flowing from a charging power supply. The control unit (9) has determined that the cell B1 has a high or higher state of charge and therefore a low or lower charge current requirement. The load packet current Ich is reduced by ^a balance current ^Ib1 for cell B1, compared to the other cells B2 to B4 receiving the full load current ^Ich flowing through switch S9 and the diode D10 in series with it. Balancing current I ^{b 1} flows through switch S1 and diode D2 which is in series with switch S1, and then flows through switching device or switch S19 and not through switching devices or switches S21 and S20 which are off. The current I ^{b 1} flows through the individual ohmic device (5), i.e. the individual resistor R1 and through the switching devices or switches 23 and S4 and the diode D3 which is in series with S4 and in parallel with the switch S3 which is off. The charging current for cell B1, which has a high or highest state of charge and therefore a lower charge current requirement, is I ^ch - I ^{b 1} . The value of current I ^{b 1} is determined by the voltage drop in cell B1 divided by the resistive impedance in circuit S1, D2, S19, R1, S23, S4, D3 which includes the resistance of resistor R1. If a higher balance current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^{b 1} . More parallel paths can be added (not shown) which add more resistors like R2 to resistor R1.

Figures 4b to d show similar charging operations, which reduce the charging current in one or more cells B1 to B4. Figure 4b illustrates the ^RESS cell pack of Figures 1 and 2 subjected to a charging current Ich flowing from a charging power supply. The control unit (9) has determined that cell B2 has a high or higher state of charge and therefore a low or lower charge current requirement. The load packet current Ich is reduced by a balance current ^Ib2 for cell ^B2 , compared to the other cells B1, B3, B4 receiving the full load current ^Ich flowing through switch S9 and diode D10 in series with it. Balancing current I ^b2 flows through switch S5 and diode D6 which is in series with switch S5. It then flows through the switching device or switch S19 and not through the switching devices or switches S21 and S20 which are off. The current I ^b2 flows through the individual ohmic device 5, ie the individual resistor R1 and through the switches S23 and S8 and the diode D7 which is in series with S8 in parallel with the switch S7 which is off. The charging current for cell b 2 , which has a high or highest state of charge and thus a low or lowest charge current requirement, is I ^ch - I ^b2 . The value of current I ^b2 is determined by the voltage drop in cell B2 divided by the resistive impedance in circuit S5, D6, S19, R1, S23, S8, D7 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^b2 . More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1. If the device is turned on switching or switch S1 instead of S5 (not shown), the reduced load current I ^ch - I ^b flows through B1 and B2.

Figure 4c illustrates the ^RESS cell pack of Figures 1 and 2 subjected to a charging current Ich flowing from a charging power supply. The control unit (9) has determined that the cell B3 has a high or higher state of charge and therefore a lower charge current requirement. The load packet current ^Ich is reduced by a balance current ^Ib3 for cell B3, compared to the other cells B1, B2, B4 receiving the full load current ^Ich flowing through switch S9 and diode D10 in series with it. Balancing current I ^b3 flows through switch S11 and diode D12 which is in series with switch S11. It then flows through the switching device or switch S20 and not through the switching devices or switches S19 and S21 which are off. The current I ^b3 flows through the individual ohmic device 5, ie the individual resistor R1 and through switches 23 and S14 and diode D13 which is in series with S14 in parallel with switch S13 which is off. The charging current for cell B3, which has a high or highest state of charge and therefore a low or lowest charge current requirement, is I ^ch - I ^b3 . The value of current I ^b3 is determined by the voltage drop in cell B3 divided by the resistive impedance in circuit S11, D12, S20, R1, S23, S14, D13 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^b3 . More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1.

Figure 4d illustrates the ^RESS cell pack of Figures 1 and 2 subjected to a charging current Ich flowing from a charging power supply. The control unit (9) has determined that the cell B4 has a high or higher state of charge and therefore a lower charge current requirement. The load packet current ^{Ich is reduced by a balance current Ib4 for} cell B4, compared to the other cells B1, B2, B3 receiving the full load current ^Ich flowing through switch S9 and diode D10 in series with it. Balancing current I ^b4 flows through switch S15 and diode D16 which is in series with switch S15. It then flows through the switching device or switch S20 and not through the switching devices or switches S19 and S21 which are off. The current I ^b4 flows through the individual ohmic device 5, ie the individual resistor R1 and through switches 23 and S18 and diode D17 which is in series with S18 in parallel with switch S17 which is off. The charging current for cell B4, which has a high or highest state of charge and therefore a low or lowest charge current requirement, is I ^ch - I ^b4 . The value of current I ^b4 is determined by the voltage drop in cell B4 divided by the resistive impedance in circuit S15, D16, S20, R1, S23, S18, D17 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^b4 . More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1. If the switching device or switch S11 is turned on instead of the switching devices or switch S15 (not shown), the reduced load current ^Ich - ^Ib flows through B3 and B4.

Figures 5a to 5d show the same ^RESS system of Figures 4a to 4d for discharge mode with a load current Ides through a load. The switching operations are equivalent to those described for Figures 4a to 4d. Figure 5a illustrates the ^RESS cell pack of Figures 1 and 2 providing a discharge current Ides into a load. The control unit (9) has determined that the cell B1 has a high or highest state of charge and therefore can provide more discharge current. The discharge current packet ^Ides is increased with a balance current I ^{b 1} for cell B1, compared to the other cells B2 to B4 experiencing discharge current ^Ides flowing through switch S10 and diode D9 in series with him. Balancing current I ^{b 1} flows through switch S1 and diode D2 which is in series with switch S1. It then flows through the switching device or switch S19 and not through the switching devices or switches S21 and S20 which are off. The current I ^{b 1} flows through the individual ohmic device 5, that is, the individual resistor R1 and through the switching devices or switches 23 and S4 and the diode D3 which is in series with S4 and in parallel with the switch S3 that is powered off. The discharge current for cell B1, which has a high or highest state of charge and therefore can provide more discharge current, is ^Ides + I ^{b 1} . The value of current I ^{b 1} is determined by the voltage drop in cell B1 divided by the resistive impedance in circuit S1, D2, S19, R1, S23, S4, D3 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^{b 1} . More parallel paths can be added (not shown) controlled by a switching device or switch that add more resistors like R2 to resistor R1.

Figure 5b illustrates the ^RESS cell pack of Figures 1 and 2 subjected to a discharge current Ides flowing through a load. The control unit (9) has determined that the cell B2 has a high or highest state of charge and therefore can supply more discharge current. The current discharge packet Ides is increased with a balancing current ^Ib2 for cell ^B2 , compared to the other cells B1, B3, B4 experiencing discharge current ^Ides flowing through switch S10 and diode D9 in series with it. Balancing current I ^b2 flows through switch S5 and diode D6 which is in series with switch S5. It then flows through the switching device or switch S19 and not through the switching devices or switches S21 and S20 which are off. The current I ^b2 flows through the individual 5 ohmic device, it is ie the individual resistor R1 and through the switches or switching devices S23 and S8 and the diode D7 which is in series with the S8 in parallel with the switch S7 which is off. The discharge current for cell B2, which has a high or highest state of charge and therefore a low or lowest charge current requirement, is ^{Ich + Ib2 .} The value of current I ^b2 is determined by the voltage drop in cell B2 divided by the resistive impedance in circuit S5, D6, S19, R1, S23, S8, D7 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^b2 . More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1 controlled by a switch. If the switching device or switch S1 is turned on instead of the switching device or switch S5 (not shown), the increased discharge current ^Ich + ^Ib flows through B1 and B2.

Figure 5c illustrates the ^RESS cell pack of Figures 1 and 2 subjected to a discharge current Ides flowing through a load. The control unit (9) has determined that the cell B3 has a high or highest state of charge and can therefore provide a higher discharge current. The current discharge packet ^Ides is increased with a balancing current ^Ib3 for cell B3, compared to the other cells B1, B2, B4 experiencing discharge current ^Ides flowing through switch S10 and diode D9 in series with it. Balancing current I ^b3 flows through switch S11 and diode D12 which is in series with switch S11. It then flows through the switching device or switch S20 and not through the switching devices or switches S19 and S21 which are off. The current I ^b3 flows through the individual ohmic device 5, i.e. the individual resistor R1 and through the switching devices or switches 23 and S14 and the diode D13 which is in series with S14 in parallel with the switching device or switch S13 which is off. The discharge current for cell B3, which has a high or highest state of charge and therefore can provide more discharge current, is ^{Ides + I b3 .} The value of current I ^b3 is determined by the voltage drop in cell B3 divided by the resistive impedance in circuit S11, D12, S20, R1, S23, S14, D13 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^b3 . More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1 controlled by a switching device or switch.

Figure 5d illustrates the ^RESS cell pack of Figures 1 and 2 subjected to a discharge current Ides flowing through a load. The control unit (9) has determined that the cell B4 has a high or highest state of charge and therefore can supply more discharge current. The current discharge packet ^{Ides is increased with a balancing current Ib4 for} cell B4, compared to the other cells B1, B2, B3 receiving discharge current ^Ides flowing through switch S10 and diode D9 in series with it. Balancing current I ^b4 flows through switch S15 and diode D16 which is in series with switch S15. It then flows through the switching device or switch S20 and not through the switching devices or switches S19 and S21 which are off. The current I ^b4 flows through the individual ohmic device 5, i.e. the individual resistor R1 and through the switching devices or switches 23 and S18 and the diode D17 which is in series with S18 in parallel with the switching device or switch S17 which is off. The discharge current for cell B4, which has a high or highest state of charge and therefore can provide more discharge current, is ^{Ides + I b4 .} The value of current I ^b4 is determined by the voltage drop in cell B4 divided by the resistive impedance in circuit S15, D16, S20, R1, S23, S18, D17 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current I ^b4 . More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1 controlled by a switching device or switch. If the switching device or switch S11 is turned on instead of the switching device or S15 (not shown), the increased discharge current ^Ich + ^Ib flows through B3 and B4.

In a further simulation, as shown in Figures 7 and 9, during sleep time, the initial SoC of the cells that are connected in series was adjusted to be 100%, 98%, 94, and 92 for the cell B1, cell B2 and cell B3 and cell B4 respectively. Because of the 8% difference in SoC between cells, the voltage difference is around 270 mV. As can be seen in Figure 9, the power loss of single and multiple ohmic devices, such as resistors (see Figure 6), is almost the same (~1.8 Wh). However, the rate of heat loss for the single ohmic device is about half that of the multi-resistance device, and therefore the temperature rise of the circuit components is reduced, increasing the life of the components. .

The equilibration time with the multiple resistors (~19 min) is less than the time required to equilibrate the cells with a single resistor (~29 min), however this time difference is not significantly greater. Therefore, in the present invention there is no need to increase the number of resistors by more than one, although the option to do so as provided in the embodiments of the present invention is advantageous. Consequently, in the embodiments of this invention, the proposed management system uses a single resistor not only for passive balancing mode but also for series and parallel balancing and AC impedance test modes thanks to the arrangement intelligent dedicated switches. This benefit offsets any small increase in balance time.

To validate the performance of the proposed control strategy for the passive balancing mode by using a single ohmic resistor, the proposed management circuit was designed and realized using Matlab/Simulink. These simulations were carried out during loading and unloading. During charging, the imbalance in the state of charge (SoC) was around 8%. Figure 10 shows the simulation results of the passive balancing mode during the charging process. Figure 11 demonstrates the simulation results of the same balancing mode during discharge under the same initial condition (8% difference in SoC). As a result, the management system proposed according to the embodiments of the present invention, especially those with a pulse width modulation (PWM) control strategy (see PWM control strategies below) has the ability to eliminate the imbalance on the voltage and the SoC by using a single ohmic device such as a passive resistor balancing mode.

Series and Parallel Balance Mode – An internally powered balance mode for downtime

In this balancing mode, the connection of some cells B1 to B4 is changed from series to parallel and, optionally, cells B1 to B4 can be disconnected from any load or load device by opening the protection relay (8). Figure 12 illustrates four operating cases of internally powered balancing modes for idle time, such as series and parallel balancing modes during idle time using, for example, a single ohmic device (5) such as as a single resistor R1, whereby Figure 12a illustrates a transfer of energy from cell 3 and cell 4 to cell 1, Figure 12b illustrates a transfer of energy from cell 3 and cell 4 of the battery cell 2, Figure 12c illustrates a transfer of energy from cell 1 and cell 2 to battery cell 3 and Figure 12d illustrates a transfer of energy from battery cell 1 and cell 2 to cell 4. It can be seen that four one-way switches (S19, S20, S21, and S22) can be used to control the direction of the balance current through the same resistor, which is used in this mode to limit the balance current. balanced.

Figure 12a illustrates the RESS cell pack of Figures 1 and 2 in idle mode. The RESS can be isolated by opening the protection relay (8). The control unit (9) has determined that the cell B1 has a low state of charge and, therefore, a greater need for charging current. The charging current Ib ¹ is supplied to cell B1 from cells B3 and B4. The switching devices or switches S9 and S10 are off. Balancing current Ib ¹ flows through switch S11 and diode D12, which is in series with switch S11. It then flows through the switching devices or switches S20 and S21 and not through the switching devices or switches S19, S23 and S22 which are off. The current Ib ¹ flows through the individual ohmic device 5, i.e. the individual resistor R1 and through the switching devices or switches S21 and S2 and the diode D1 which is in series with S2 and in parallel with switch S1. which is off. The charging current for cell B1 is Ib ¹ . The value of the current Ib ¹ is determined by the voltage drop in cells B3 and B4 in series minus the voltage drop in cell B1, by the resistive impedance in the circuit S11, D12, S20, R1, S21, S2 , D1, S3, D4, S18, D17 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current Ib ¹ . More parallel paths (not shown) can be added which add more resistors like R2 to resistor R1 and controlled by a switch or switching device.

Figure 12b illustrates the RESS cell pack of Figures 1 and 2 in idle mode. The RESS can be isolated by opening the protection relay (8). The control unit (9) has determined that the cell B2 has a low state of charge and, therefore, a greater need for charging current. The load current Ib ² for cell B2 is supplied to cell B2 from cells B3 and B4, the switching devices or switches S9 and switch S10 are off. Balancing current Ib ² flows through switch S11 and diode D12 which is in series with switch S11. It then flows through the switching devices or switches S20 and S21 and not through the switching devices or switches S22, S23 and S19 which are off. The current Ib ² flows through the individual ohmic device 5, i.e. the individual resistor R1 and through the switches or switching devices S21 and S6 and the diode D5 which is in series with S6 in parallel with the switch S5 which is turned off. The value of the current Ib ² is determined by the voltage drop in cells B3 and B4 minus the voltage drop in cell B2 divided by the resistive impedance in the circuit S11, D12, S20, R1, S21, S6, D5 , S7, D8, S18, D17 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing the current Ib ² . More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1 controlled by a switching device or switch.

Figure 12c illustrates the RESS cell pack of Figures 1 and 2 in idle mode. The RESS can be isolated by opening the protection relay (8). The control unit (9) has determined that the cell B3 has a low state of charge and, therefore, a greater need for charging current. The switching devices or switches S9 and S10 are off. Balancing current Ib3 is provided by cells B1 and B2 and flows through switch S1 and diode D2 which is in series with switch S1. It then flows through the switching devices or switches S19 and S22 and not through the switching devices or switches S20, S23 and S21 which are off. The current Ib3 flows through the individual ohmic device 5, i.e. the individual resistor R1 and through the switches or switching devices S22 and S12 and the diode D11 which is on. series with S12 in parallel with switch S11 which is off. The value of current Ib ³ is determined by the voltage drop across cells B1 and B2 in series minus the voltage drop across B3 divided by the resistive impedance in circuit S1, D2, S19, R1, s 22, S12, D11, S13, D14, S8, D7 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing current Ib3. More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1 controlled by a switching device or switch.

Figure 12d illustrates the RESS cell pack of Figures 1 and 2 in idle mode. The RESS can be isolated by opening the protection relay (8). The control unit (9) has determined that the cell B4 has a low state of charge and therefore a need for charging current. The switching devices or switches S9 and S10 are off. Balancing current Ib4 is provided by cells B1 and B2 and flows through switch S1 and diode D2 which is in series with switch S1. It then flows through the switching devices or switches S19 and S22 and not through the switching devices or switches S20, S23 and S21 which are off. The current Ib4 flows through the individual ohmic device 5, i.e. the individual resistor R1 and through the switches or switching devices S22 and S16 and the diode D15 which is in series with the S16 in parallel with the switch S15 which is off. The value of current Ib4 is determined by the voltage drop across cells B1 and B2 in series minus the drop across B4 divided by the resistive impedance in circuit S1, D2, S19, R1, S22, S16, D15, S17, D18, S8, D7 which includes the resistance of resistor R1. If a higher current is desired, the switching device or switch S24 can be turned on and resistor R2 is connected in parallel with R1, thereby reducing the resistance and increasing current Ib4. More parallel paths can be added which add more resistors like R2 (not shown) to resistor R1 controlled by a switching device or switch.

Figure 12: Four cases of series and parallel balancing mode operation during sleep time by using a single resistor: a) transfer power from cell 3 and cell 4 to battery cell 1, b ) transfer power from cell 3 and cell 4 to battery cell 2, c) transfer power from cell 1 and cell 2 to battery cell 3, and d) transfer power from cell 1 and cell 2 cell battery 4

Furthermore, embodiments of the present invention provide the ability to integrate the RESS, as a battery pack, into an electrical grid by charging and discharging from the same port, as shown in Figure 2.

Furthermore, as shown in Figure 13, embodiments of the present invention have the ability to charge and discharge the batteries from different ports through the use of a separate DC charger (20).

The external DC charger 20 may be connected or connectable to a junction point between the switching devices or switches S21 to S22. These switching devices or switches control access to cells B1 to B4. The RESS can be isolated by opening the protection relay (8).

For example, the current path from the DC charger (20) may be through the switching device or switch S21 (S23 is off) S2, D1, load cells B1 and B2, through switch S7 and D8 in series with S7 and from there to ground. This charges cells B1 and B2. If only B1 is to be charged, then the return path to ground can be via ignition switch S3 and diode D4 in series with S3 to ground. If only B2 is to be charged, the path from DC charger 20 is through switch S6 with diode D5 in series with switch S6 and return to ground is through S7 and D8.

A second charging path is from the DC charger (20) (in parallel to the charging paths mentioned above), via power switch S22, switch S12 and diode D11 in series, load cells B3 and B4, through switch S17 and diode D18 in series with S17 to ground. If only B3 is to be charged, the return path to ground can be via S13 and diode D14. If only B4 is to be charged, the path from charger (20) is via ignition switches 22 and S16 and diode D15. Return to ground is done by switch S17 and diode D18 to ground.

To validate the performance of the series and parallel balancing mode compared to the passive balancing mode using a single ohmic resistor, the same initial conditions (270 mV difference in voltage between cells and 8% difference in voltage between cells) were used. difference in SoC) to compare between two balancing modes as shown in Figure 14. To test the ability of the proposed control strategy to eliminate any difference in SoC level, the SoC of cell 1 and cell 2 has been tuned to the same level (100% SoC) and the same SoC for cell 3 and cell 4 (92%).

It is clear from Figure 14 that the passive balancing mode was able to remove the unbalance faster (31 min) than using the series and parallel balancing mode (56 min). The selection of the balance time depends primarily on the application to identify the amount of use of the battery pack per day. However, in the present invention, the balancing time could be adjusted by changing the value of the balancing ohmic device (i.e. decreasing the balancing ohmic resistance, e.g. by paralleling resistors) leads to an increase in the balancing ohmic resistance. balancing current and thus decreases the balancing time).

To illustrate the main advantage of using a series and parallel mode during sleep time, Figure 16 shows that balanced series and parallel mode has the ability to reduce power loss by 80% compared to the passive balanced mode, because the series and parallel balanced mode provides a discharge path between the higher and lower energy cells. For example, as can be seen in Figure 15, the SoC of cell 1 and cell 2 decreased from 100% to 95% and the SoC of cell 3 and cell 4 increased from 92% to 94.5% at because of the use of the balancing mode in series and in parallel. In passive mode, the cell 1 and cell 2 SoC decreased by 6% by dissipating power into the individual ohmic resistor.

Pulse Width Modulation (PWM) Control Strategies

To overcome the SoC and voltage imbalance between the cells that are connected in series, a control strategy based on the PWM technique was developed as shown in Figure 17 that can be used with any of the embodiments of the present invention. . As described above, balancing modes primarily rely on either discharging energy from the higher energy cell to the lower energy cell (in the case of series and parallel mode) or dissipating energy into a single ohmic resistor ( in the case of passive mode), which means that the balancing is done in a cell-by-cell balancing manner. This section describes the control strategy that has been designed for lithium-ion batteries, for example.

However, this control can be modified for use in different energy storage technologies. In the case of lithium-ion battery cells, the OCV voltage is almost flat, and the difference between the voltage at 100% SoC and 0% SoC is about 600 mV. Therefore, the battery management system must disconnect the battery pack to protect it when the difference between the voltages of the cells in the set exceeds a limit value, e.g. g., more than 300 mV (during sleep time).

In Figure 17, the inputs to the control scheme are the voltage of all the cells that are connected in series. The maximum and minimum voltages are then calculated to identify the highest and lowest power cell based on the cell voltage. Subsequently, the voltage difference (AV) (200) is limited (201) by using the saturation block. The output of the saturation block (AV ^l ) (202) varies between 0 and 200 mV, and then the value per unit (PU) (203) (AV ^lpu ) (204) is calculated by (AV ^l (202) / 200 mV) in order to obtain the voltage difference (AV ^{lp u} ) (204) changing from 0 to 1. The output of the PU block (203) is compared with the carrier wave (205) (that is, positive ramp or negative ramp). negative or triangle wave) to generate the switch pulse signal (206). The switch pulse signal 206 is used as drive signals to control the switches. For example, in passive mode, the switch pulse signal can be used to activate the switching devices or switches S1, S19, S23, S4 in order to lower the high energy of the battery cell B1.

As can be seen in Figure 18, the switch pulse signal (209) can be generated by calculating the intersection points between the voltage differences (AV ^{lp u} ) (208) and the carrier wave (207), as. The pulse signal is primarily used to open the cell's discharge path, which has the highest voltage compared to the rest of the cells in the array.

A carrier waveform is used to keep the pulse rate constant. To validate the performance of the PWM control strategy to accurately implement the balancing modes, different balancing modes based on the PWM control strategy have been designed and investigated.

AC impedance test mode

Embodiments of the present invention include one or more diagnostic tests selected from current diagnostic tests, voltage diagnostic tests, and resistance or impedance diagnostic tests, e.g. eg, as set forth in US 4,719,427 and US 4,361,809 which are incorporated herein by reference. An advantage of embodiments of the present invention is that an external function generator with switches is not needed to apply a sinusoidal signal such as a small sinusoidal signal to calculate the AC impedance of the battery cell.

In this embodiment, a DFP or SoH mode is provided for a system, procedure, or device with the same configuration (e.g., bidirectional and unidirectional switches optionally connected to a single ohmic device, such as a resistor) that is used to balance , as described above with reference to Figures 1, 2, 4, 5, 12, 13. It is not necessary to use an external supply. In this embodiment, a diagnostic parameter of a cell or cell pack, such as battery cells, e.g. g., the SoH. For example, the SoH of a rechargeable energy storage cell can be estimated from the results of applying an AC impedance test mode. For example, a square or quasi-square wave or, in general, a pulse width modulation signal, e.g. eg, a current signal, to a cell or cells in a battery pack and measure the response voltage signal. To generate the pulses, such as square wave or quasi-square wave current pulses, for example, a DFP can be used to, for example, select a group of cells from all cells B1 to B4. The selected cell group can be used as a DC source to test another cell group of the same battery and vice versa, e.g. without the need for an external power supply or DC/DC converter. The RESS can be isolated by means of the protection relay (8).

For example, a pulsed current such as a square or quasi-square wave current can be applied to one or more cells and the voltage of the response signal recorded. Figure 19 illustrates a flow chart (300) for this embodiment for estimating the SoH and/or SoC of a battery cell(s). This procedure comprises or consists of an electrochemical impedance spectroscopy (EIS) test, e.g. eg, comprising the step of applying a periodic current waveform (eg, a square wave) to a battery cell or cells under test and measuring a response voltage waveform. To generate the square wave current, one group of cells can be used as a DC source to test another group of cells (eg, comprising one or more cells from the same battery) and vice versa.

The procedure begins at step 302, and at step 304 the periodic current signal such as a square wave current signal is applied to one or more cells and the applied current signal and the one or more signals from the current are measured. response tension. In step 306, the measured voltage and current signal in the time domain is transformed into the frequency domain by using DFT (Discrete Fourier Transform). From the voltage and current signals in the frequency domain, an AC impedance of the battery cell(s) is calculated in step 308 by dividing the voltage by the current in the frequency domain, and then the resonance impedance (the lowest value of AC impedance, eg, AC impedance at 1 kHz (see Figure 21) is calculated to estimate the SoH of the battery cell(s) in step 309.

To validate the capacity of the management system of the invention that performs the AC test mode, the results are shown in Figure 20.

For example, in case 1 of Figure 20, cell B3 and cell B4 are used as a DC source to apply the positive pulse in battery cell B1, while the negative pulse is formed by connecting cell B1 in parallel with R1.

The drive current and response voltage signal are captured in the time domain and transformed into the frequency domain using DFT (Discrete Fourier Transform). From the voltage and current signals in the frequency domain, an AC impedance of the battery can be calculated as illustrated in Figure 21. As shown in Figure 21, the resonance impedance (R ^im ) represents the lowest value of the AC impedance, indicating that the imaginary part of the impedance (Im {Z} =0) is equal to zero. In fact, the real part is the only part that stays around 1 kHz (which is the resonant frequency). Consequently, at the resonant frequency point, the capacitive and inductive impedances cancel each other out, and thus the battery impedance becomes purely resistive, which is called the resonant impedance or internal resistance of the battery cell. drums. RIM can be performed on battery cells regardless of their SoC levels, since there is no effect of SoC levels on the R ^im value.

The resonance impedance ( Rim) has been calculated from the minimum impedance zone as well as the capacity of different types of battery by using different life cycle profiles. Therefore, independently or for use with any of the embodiments of the present invention, methods, systems and devices are provided adapted to determine the relationship between SoH and resonance impedance by performing the calculation (see Figure 22) of the equation 1:

where C is a calibration constant, which can be used to fit the confidence limits of the curve. The value of constants A and B are mainly based on the initial value of the AC impedance which is often declared on the battery data sheet. At 100% SoH let VSoH 4- C SoH+C+C be about 10%, where C is a constant < 1% (eg, ~0.1537%). Since A and B are constants, they can be calculated as follows:

Therefore, these constants are calculated by using Equations 2 and 3:

_{B = (R im lm ix} (3)

Where Rnc is the initial resonance impedance, ( Rim)max is the maximum value of the resonance impedance. Equation (1) can be rewritten as follows:

^r . — A -I-------------- lm VSoH C

To validate the aging model, batteries with different chemistry types and capacity rates were subjected to this test and the SoH results obtained were compared with the SoH results calculated by a capacity test based on the nominal and remaining capacity of the battery. drums. Table 1 includes a comparison of the results, and it can be seen that the difference in SoH estimation between the two procedures (AC impedance at resonance frequency and capacitance test) is around 3%.

Table 1: Validation of the SoH estimate

The actual SoH was measured by performing capacity tests at 1 lt before applying the RIM to estimate the SoH of the Cn {Ah) cells.

used battery. It (amps) (reference test current) is defined as 1^, where Cn is the cell rating and n is the time base (h). As can be seen in Figure 24, the solid line represents a zero difference between the actual and predicted SoH. Although lithium-ion battery cells have been tested under different load conditions, it is important to note that the largest error obtained was 4.1%. In fact, the average error of the validation data (27 points) is 2.8%.

Furthermore, these AC impedance determinations at 1 kHz or also known as "resonance impedance procedure" (RIM) have been performed to estimate the state of health (SoH) of lithium-ion battery cells. In addition, this procedure provides a fast, simple, and accurate testing regimen for testing, characterizing, and classifying used second-life batteries. All used battery cells have been subjected to a potentiostatic electrochemical impedance spectroscopy (EIS) mode by applying a small AC voltage (e.g. 10mV) over the DC voltage of the battery and measuring the response current within the frequency range of 50 mHz to 10 kHz by using a biological impedance spectroscopy device and EC-lab V10,21 software. To perform this procedure, the EIS results of 43 commercial lithium-ion battery cells (LFP, NMC) have been used to check the ability to use the RIM to estimate the SoH of lithium-ion battery cells. Table 2 illustrates the cell chemistry types tested, indicating the battery shape and capacity of high power, high energy battery cells.

Table 2: Technical specifications of lithium-ion battery cells tested

Resonance impedance has been measured at 1 kHz for all tested battery cells, which have been subjected to different aging tests. The relationship between health status (%) and Rim impedance are shown in Figure 23. It is clear from this Figure that Rim value is strongly related to battery health status for all battery cells. tested. From Figure 23, the EIS results reveal that the relationship between SoH and Rim only appeared to be linear between 100% SoH and 80% SoH. However, it is clear that this relationship became non-linear when the SoH of the battery cells decreased below 80% SoH.

The methods of these embodiments can be used to identify the end of life of used or second life batteries, for example, in stationary applications. With these procedures, the battery life can be predicted based on the impedance value of the resonance. The lowest SoH of the first life battery is typically about 80%. From the aging model according to the realizations of the In the present invention, the resonance impedance difference is divided by the associated SoH difference to calculate the rate of increase of Rm p. e.g., for each unit change of SoH, e.g. eg, for every 1% decrease in SoH.

For batteries tested in the range of 100% to 80% SoH, the Rim value increases by 0.08 mQ with each 1% decrease in SoH. Rim rate of rise increases with decreasing battery SoH. Then, for example, for the range from 20% to 0% SoH, the Rim value increases rapidly by about 2.13 mQ with every 1% SoH decrease. Consequently, battery cells operating at 20% to 0% SoH may become hot due to their increased internal impedance and may also swell. Also, battery cells at less than 20% SoH cannot provide power for more than 12 min at 11t.

An evaluation procedure based on RIM values for testing and classifying second life batteries to determine which battery cells are considered reusable according to one embodiment of the present invention includes the following steps after the used cells have been visually examined to separate cells/modules with obvious physical damage, leaks, oxidized layers, cell deformation, or other signs of abuse, the procedure comprising the steps: voltage verification whereby a voltage measurement will be performed to identify cells/modules that have failed (for example, due to short circuits or dry separators), and

evaluation process by which the SoH is estimated by applying the resonance impedance methodology and using the generic aging model.

To measure the AC impedance of the battery cells, an EIS device can be used to generate a 1 kHz sinusoidal waveform over the DC voltage of the battery cells and measure the response current. In practice, due to the use of a very small sinusoidal signal (approximately 10 mV or 10 mA), an advanced filter and robust algorithm is needed to calculate the AC impedance and eliminate the influence of noise and interference from surrounding devices. . Therefore, a periodic signal (i.e. in the form of a square wave) at a low frequency (approximately 100 mHz) can be designed with a simple low-pass filter to avoid the influence of noise or any interference in the measurement unit. This procedure can be implemented offline to test and classify second life battery cells or online as a function of the battery management system to estimate the SoH of the battery cells.

The methods according to the present invention can be carried out by a control unit (9) with processing capacity such as that provided by one or more microprocessors, FPGA or a central processing unit (CPU) and/or a graphics processing unit (GPU), and which is adapted to carry out the respective functions by programming with software, that is, one or more computer programs. References to software may include any type of program in any language executable directly or indirectly by a processor, either through a compiled or interpretive language. The implementation of any of the methods of the present invention can be carried out by means of logic circuits, electronic hardware, processors or circuits that can include any type of logic or analog circuits, integrated to any degree, and without being limited to general purpose processors, processors of digital signals, ASICs, FPGAs, discrete components or transistor logic gates and the like.

Said control unit (9) may have memory (such as a non-transient computer readable medium, RAM and/or ROM), an operating system, optionally a display such as a fixed format display, ports for data input devices such as a keyboard, a pointing device such as a "mouse", serial or parallel ports to communicate with other devices, network cards and connections to connect to any of the networks.

The software can be adapted to perform a management method for rechargeable energy storage devices comprising series-connected energy storage cells and switching devices for dividing the series-connected energy cells into groups of cells, the method comprising : Enable switching devices to select either externally powered or internally powered cell balancing and an internally powered diagnostic test. The software may be incorporated into a computer program product adapted to perform the functions detailed below when the software is loaded into the controller and executed on one or more processing engines, such as microprocessors, ASICs, FPGAs, etc. Thus, a control unit 9 for use with any embodiment of the present invention may incorporate a computer system that can run one or more computer applications in the form of computer software.

The above method can be performed by one or more computer application programs running on the computer system by loading them into memory and running on or associated with an operating system, such as, Windows™ supplied by Microsoft Corp, USA, Linux , Android or similar. The computer system may include main memory, preferably random access memory (RAM), and may also include a non-transient hard disk drive and/or removable non-transient memory and/or non-transient solid-state memory. The non-transient removable memory can be an optical disc such as a compact disc (CD-ROM or DVD-ROM), a magnetic tape, which is read and written by a suitable reader. Removable memory is not transient may be a computer-readable medium on which computer software and/or data are stored. Non-volatile storage memory can be used to store persistent information that should not be lost if the computer system is powered off. Application programs can use and store information in non-volatile memory.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines, such as microprocessors, ASICs, FPGAs, etc.: a individual ohmic device that determines the level of the balancing current, and/or

an additional ohmic device connected in parallel with the individual ohmic device to change the resistance value to determine the balance current level.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines such as microprocessors, ASICs, FPGAs, etc.: activation bidirectional and unidirectional switching devices to select operating modes.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines, such as microprocessors, ASICs, FPGAs, etc. :

Using one group of cells to apply a drive current to test another group of cells. A subsequent step is to measure a response voltage signal on the drive current.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines such as microprocessors, ASICs, FPGAs, etc.: external power balancing modes in passive balancing mode during charging or discharging of the RESS, and/or internally powered cell balancing in a series and parallel mode balancing during a sleep time.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines such as microprocessors, ASICs, FPGAs, etc.: a mode passive balancing that protects rechargeable energy storage cells from overcharging or overdischarging.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines such as microprocessors, ASICs, FPGAs, etc.: a series and parallel mode that performs full balancing of rechargeable energy storage cells during a sleep time.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines, such as microprocessors, ASICs, FPGAs, etc. :

converting the response voltage signals from the time domain to the frequency domain using a discrete Fourier transform and means for calculating AC impedance as a function of frequency levels. A later stage is to calculate an AC impedance to estimate the SoH of the rechargeable energy storage cells.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines, such as microprocessors, ASICs, FPGAs, etc. : estimation of the SoH of rechargeable energy storage cells using a generic aging model.

The software embedded in the computer program product is adapted to perform the following functions when the software is loaded onto the respective device(s) and executed on one or more processing engines, such as microprocessors, ASICs, FPGAs, etc. :

The generic aging model relates the resonance impedance to the state of charge, for example, in

D

Rlm = A.

the model, the resonance impedance is defined by: v soh+c ■ in which A, B and C are constants.

Any of the above programs may be implemented as a computer program product that has been compiled for a processing engine on any of the servers or nodes in the network. The computer program product may be stored on a non-transient signal storage medium, such as an optical disk (CD-ROM or DVD-ROM), a digital magnetic tape, a magnetic disk, a solid-state memory such as a memory USB flash, a ROM, etc.

Claims (16)

1. A management system for rechargeable energy storage devices comprising energy storage cells connected in series (B1, B2, B3, B4, Bn) and a control unit (9), characterized in that said management system also includes • a cell division circuit (2) comprising switches (S9, S10) configured to divide the series-connected energy storage cells (B1, B2, B3, B4, Bn) into groups of cells, • a mode selection circuit (3) comprising switching devices and an individual ohmic device (5) and in which the switching devices are configured to select any of: a) externally powered cell balancing, where externally powered cell balancing is a passive balancing mode during charging or discharging of rechargeable energy storage devices, b) balancing of cells with internal power supply, in which the balancing of cells with internal power supply is a balancing in series and parallel mode during a rest time, and c) an internally powered diagnostic test for state of health or state of charge estimation, wherein a group of cells of said divided cell groups with the cell division circuit (2) is adapted to apply a excitation current to test another group of cells of said groups of cells, and wherein said individual ohmic device (5) determines a balancing current level for said passive balancing and for said series and parallel mode balancing. The management system of claim 1 further comprising an additional ohmic device (6) connected in parallel with the individual ohmic device (5) to change a resistance value that determines the balance current level. The management system of any preceding claim, wherein the mode selection circuit switching devices comprise bidirectional and unidirectional switches. 4. The management system of any preceding claim, wherein said passive balancing mode is adapted to protect rechargeable energy storage cells from overcharging or overdischarging. 5. The management system of any of the preceding claims, wherein said serial and parallel mode is adapted to complete the balancing of the rechargeable energy storage cells during sleep time. 6. The management system of any preceding claim further comprising means for measuring a response voltage signal in the drive current. 7. The management system of claim 6, further comprising means for converting the response voltage signals in the time domain to the frequency domain by using a discrete Fourier transform and means for calculating an impedance of AC as a function of frequency levels, and wherein the management system is further adapted to estimate the SoH of the rechargeable energy storage cells by using said AC impedance. 8. The management system of any of the preceding claims, adapted to estimate a SoH of rechargeable energy storage cells by using a generic aging model. 9. A management method for rechargeable energy storage devices comprising series-connected energy storage cells (B1, B2, B3, B4, Bn) and a mode selection circuit (3) comprising switching devices and an individual ohmic device (5), the method comprising: • activating the switching devices of the mode selection circuit (3) to select any of: a) balanced cells with external power, in which the balanced mode with external power is a passive balancing mode during charging or discharging of rechargeable energy storage devices, b) balancing of cells with internal power supply, in which the balancing of cells with internal power supply is a balancing in series and parallel mode during a rest time, and c) an internally powered diagnostic test for estimation of state of health or state of charge, • when the internally powered diagnostic test is selected, divide the series-connected power cells into cell groups and apply an excitation current to one group of cells from those cell groups to test another group of cells from those cell groups. cell groups, • when passive or series and parallel mode balancing is selected, the individual ohmic device (5) is used to determine a balancing current level and draw the balancing current or inject the balancing current into one or more rechargeable power cells. The management method of claim 9, further comprising changing a resistor value that determines the balance current level using an additional ohmic device (6) connected in parallel with the single ohmic device (5). The management method of claim 9 or 10, wherein said passive balancing mode is adapted to protect rechargeable energy storage cells from overcharging or overdischarging, and/or wherein said series mode and in parallel is adapted to complete the balancing of rechargeable energy storage cells during standby time. The management method of any of claims 9 to 11, further comprising measuring a response voltage signal in the drive current. 13. The management method of claim 12, further comprising converting signals from the response voltage in the time domain to the frequency domain by using a discrete Fourier transform and calculating an AC impedance as a function of the frequency levels and estimating the SoH of rechargeable energy storage cells by using said AC impedance. 14. The management method of any of claims 9 to 13, further comprising estimating an SoH of the rechargeable energy storage cells by using a generic aging model. 15. A computer program product which, when executed on a processing engine, implements a management system of any of claims 1 to 8 or the method of any of claims 9 to 14. 16. Non-volatile signal storage media that store the computer program product of claim 15.